Along,long time ago, I wrote letters in French to a Belgian girl whose native language was Flemish, and she spoke no English, while I spoke no Flemish.
the results would no doubt be entertaining to anyone fluent in all 3 languages, but we managed to communicate (I hope).

I remember the heroic efforts of the chap who wrote an English>Portuguese phrasebook, armed with only an English>French dictionary and a french > Portuguese dictionary.